re: Louisiana Tropical Fruit Gardening - Experiences and Updates

So why Gary's or a custom mineral forward mix? Because it breathes and doesn't break down. They tell you that drainage is important but no one ever explains why. Roots need oxygen, moisture (not water), and nutrients in that order. The more water retention your soil has, the more likely you are to suffocate and rot your roots.

The horticultural industry and academia are wrong about this. You do not want a "rich" soil full of compost unless your only goal is to grow vegetables in a single season and then discard the soil and plant. Roots do not "eat" nutritious soil. They eat glucose made by the leaves and they absorb, using ambient moisture, nutrients in the soil. In nature, the dead leaves, animals, etc. are on the surface of the soil, not deep down. Below that layer of detritus is either sand, silt, clay, or a mix of the same. Go get a shovel and dig in your yard. Unless you live in the rainforest, you'll hit sand/silt/clay less than a foot down and usually less than 6 inches down. You want your nutritious organics on top of your soil, not mixed throughout.

So why is this principle so important? Because every last bag of soil at your local big box store and even at your speciality nursery is going to be made primarily from "recycled forest products." 50 years ago the horticultural industry figured out that they could bag the wood waste by-products of the timber industry and call it "soil." It was plentiful. It was cheap and in some cases free. It was light and reduced freight costs. Most importantly, it worked! But only for about 9 months on average. It holds moisture well and the bark chunks are usually large enough to provide good aeration for the roots. It works just long enough to start a seed or cutting, ship it from a wholesaler to a vendor, sell it to a customer, and take it home to grow. After about a year, plants start to decline despite no change in the fertilizing or watering habits. This is because all that bark and sawdust is decomposing into finer and finer particles and sinking to the bottom of the pot where they become an anaerobic sludge. The chemical process of decomposition consumes oxygen. Here is a picture of that from one of my old citrus pots:

That bottom layer was not allowing water to drain and it stunk from the rotting wood. This was the very early stage of this and I ended up cutting the bottom third off of that entire root ball. The particles are so fine that they do not breathe and water stays stuck to it. Roots cannot get the oxygen they need and they get attacked by bacteria and fungi while they are weak. Root rot begins and unless you change out the soil and prune the dead roots the plant is likely to die.

But how are we supposed to retain moisture and give plants nutrition if we can't use these rich organic soils? Well, we need our nutrients to come from either fertilizer or compost on the top layer of the pot or from a liquid fertilizer. I use a top layer of compost with osmocote and water with fish emulsion every so often. But we still need something organic that will hold moisture and give the soil structure. There are a few ways to do this:

1) use about 1/3 peat in your mineral based potting mix. Yes, peat is organic but it decomposes extremely slowly. It has already been dead for thousands of years at the bottom of a lake and it is not going to rot away the same way a fresh wood chip will. It is a great consistency, light weight, and holds moisture (not water) extremely well.

2) grow your plant in fired clay pellets. This is hands down the best and most expensive medium to use. It absorbs water and stays moist, it holds on to nutrients that wash over it, and it breathes extremely well. Roots love it. This is what the high end marijuana growers use for crops that need the best care possible. It is not really feasible for most people or for our container fruit project.

3) use about 1/3 coconut coir in your mineral based mix. Coir serves the exact same role as peat, with the only difference being cost and state of decay. Coir is cheaper than peat and it has not been dead long. Because of that, the cells are still full of plant tannins that can hurt certain plants growing in it. I simply don't see a major advantage that coir has over peat.

4) use about 1/3 rice hulls in your mineral based mix. Rice hulls are almost pure silica and basically don't decompose. They provide excellent and permanent structure, aeration, and drainage to your soil. They do not hold moisture well and you will have to water a ton.

For 90% of people reading this, the answer is to make your own soil with a mix of peat, perlite, and sand. 1/3 of each would be fine. The pumice and biochar are nice but usually expensive and the pumice is heavy and hard to find. A great pumice substitute is coarse decomposed granite from your big box store. I use Gary's because I'm a nutcase and can afford it and I want the best for my permanent pots but it is definitely not necessary or cost conscious.

CONCLUSION: you are better off growing your plants in pots of pure sand and using a liquid fertilizer than you are with a bagged potting soil containing wood waste. Build your soil out of permanent minerals and let the nutrients wash down to the roots from above.

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I did order a Spanish lime and a few varieties of guava.

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Hell yeah. Which guavas did you go with? Probably the easiest container tropical fruit for beginners.

Post pics when you get your stuff in. You may want to do some pruning to encourage the right kind of growth. Guava wants to be a multi-trunked bush like a mini crepe myrtle. You have to choose a central leader stem and turn that into the trunk via pruning if you want it to be a "tree." Much much easier if you start early.

Can't wait to see how that Spanish Lime turns out. Nobody ever got delicious tropical fruits in Louisiana without pushing the envelope to see what is possible.

Nurse them through about 5 winters and you may get to keep them. Good luck.

Yeah the geffner and emperor are new to me but my bottom lows with greenhouse are upper 40s and my average lows for January and February are in the 60s. Above 60F is warm enough for good cellular respiration for everything but like coconuts and durian. Lychee and atemoya are both subtropical with the former needing about 150 chill hours to bloom and the latter being semi deciduous and dropping leaves each winter. And the really sensitive stuff does great in my grow room at 78F and 75% humidity.

I have a Wurtz avocado in a pot from last year and Glenn Mango I just ordered.

Those will go w/ my Lisbon lemon and Persian lime.

Here's to hoping!

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have you gotten to eaten any of the ice cream banana's?

I was looking into getting that one a few months ago and never pulled the trigger.

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Not from my trees yet, but I have eaten them from other trees. The biggest difference is texture. It's like a dense custard. The flavor is awesome. Sweeter than a Cavendish with vanilla notes.

The plant itself is an absolute tank. When temps start dropping into the low 50s my Cavendish type bananas start yellowing and can't metabolize well. The namwah keeps trucking until about 28 or 29 before I start seeing damage. And if the freeze doesn't last long or you wrap it to protect it will shrug it right off. Here are some pics of mine while protected.





If you don't protect during deep long freezes it will die to the ground and come back in the spring, but not fruit. You have to get a stalk through one winter to fruit.

If fruit is your main goal get the dwarf namwah. The regular namwah/ice cream is tall and you will need a ladder to harvest.

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So I don't have avocados but I know someone who does and he says the key is to be able to water them frequently but have all the water drain away immediately. More than any other tree, they are somehow water hogs and very sensitive to wet roots. It's all about sandy soil.

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Good to know!

I will be getting my first mango at the end of this month. If you are growing in a container, Pickering is probably your best bet IMO. Do all the research about care in advance. It's not a beginner tree or a learn as you go thing if you do not live in zone 10 or above. You will need a very porous soil with lots of sand, at least a 25gal pot for decent fruiting, and will need to control for both powdery mildew and anthracnose during the flowering and fruit set stages by spraying with copper and sulfur. Their natural habitat is actually quite low in humidity and has lots of drying wind, so the muggy gulf south in summer is very likely to cause fungal issues. If you let it fruit before it is large and thick enough, you risk breaking limbs and stunting the tree's growth.

wiltznucs who has already posted in this thread is going to be much more knowledgeable than me about this as he has many mangos in cultivation in central Florida.

Do all these citrus trees self pollinate?
It doesnt' say anythign about it when I'm looking them up on sites like Everglades.

I know when I was looking at apple and cherry trees it was specific about needing another tree for pollinating.